Many outdoor activities require performance footwear designed for use in extreme conditions. Performance footwear such as hiking boots, ski boots, snowboard boots, mountaineering boots, etc., can provide the wearer with protection from extreme temperatures, from moisture, and from foot injuries due to difficult terrain. To provide such protection, performance footwear is typically constructed from a material or a combination of materials having insulative, moisture resistant, and abrasion resistant characteristics.
The processes for constructing performance footwear can be labor intensive and costly and often require sophisticated and expensive molding and stitching equipment. For example, constructing performance footwear from leather requires hand cutting and hand stitching of the leather. Likewise, constructing performance footwear from plastic materials necessitates the use of expensive and complicated high-pressure injection equipment and molds.
In addition, the construction of performance boots often necessitates multiple layers of materials to be applied in sequence to one another to provide the desired insulative, moisture resistant, and abrasion resistant properties. This can result in bulky and heavy footwear that is uncomfortable to wear and difficult and time consuming to manufacture.
The present invention provides methods of manufacturing footwear and footwear uppers that simplifies the footwear manufacturing process, reduces manufacturing costs, and results in the construction of comfortable footwear having the properties necessary for use in extreme conditions. Moreover, the methods of the present invention provide the flexibility to vary the properties of the resultant footwear, allowing the footwear to be specifically tailored to the environment in which it is designed to be used, without the need for multiple sets of molds or manufacturing equipment.
In accordance with one aspect, the present invention provides a method of manufacturing a footwear upper having a three-dimensional geometry. The method includes the steps of forming a composite sheet from two or more layers, heating the composite sheet, and compression molding the composite sheet into the three-dimensional geometry of the footwear upper. The composite sheet can be formed by the lamination of two or more layers. The layers can be bonded together by a bonding agent, can be heat bonded, or can be laminated together by other means.
It is preferable that one or more of the layers forming the composite sheet includes a thermoformable material. In one preferred embodiment, the composite sheet comprises a first layer of thermoplastic foam and a second layer of thermoplastic urethane (TPU), preferably in the form of a TPU film. The thermoplastic foam can be, for example, ethylene vinyl acetate (EVA) foam. A third layer of fabric can be interposed between the first and second layers. Suitable fabrics can include a mesh fabric formed from nylon, polyester, polycotton, cotton, acetate, or acrylic.
In accordance with another aspect of the present invention, the composite sheet can comprise a first layer of cloth material, a second layer of thermoplastic foam, and a third layer of cloth material. The cloth material can be formed from felt, wool, fur, hair, polyester, nylon, cotton, acetate, or acrylic. In one embodiment, the composite sheet can be formed by needle punching the first, second, and third layers to thread the fibers forming the cloth material of the first and third layer through the second layer, thereby coupling the three layers together.
In accordance with a further aspect of the present invention, the step of compression molding includes the steps of positioning the composite sheet in a first mold member having a mold cavity and compressing the composite sheet in the mold cavity with a second mold member. The composite sheet can be heated prior to positioning the composite sheet into the first mold member or after the composite sheet is positioned in the first mold member, for example when the composite sheet is positioned in the mold cavity of the first mold member. The composite sheet can be compression molded into separate sections which are assembled after molding to form the footwear upper. Alternatively, the composite sheet can be compression molded into a seamless, unitary footwear upper that requires minimal, if any, assembly for completion.
A method of manufacturing footwear in accordance with the present invention includes the steps of constructing an upper by forming a substantially planar composite sheet from two or more layers, heating the composite sheet, and compression molding the composite sheet into the three-dimensional geometry of the upper. The upper can then be attached to a sole. The upper can be attached to the sole by stitching a sock into the upper, placing the upper on a last, attaching the upper to the sole, and removing the last from the upper after attaching the sole to the upper.
In accordance with another aspect of the present invention, an inner liner can be assembled within the upper. The inner liner can be a fabric or composite booty that can be stitched to the upper or can be separate and removable from the upper. In the alternative, a layer forming the inner liner can be attached to the composite sheet prior to the step of compression molding the composite sheet.
A multi-layer composite footwear upper in accordance with one aspect of the present invention can include a first layer of thermoplastic foam and a second layer of thermoplastic urethane (TPU), preferably in the form of a TPU film, attached to the first layer. The composite upper is preferably of unitary, seamless construction. A third layer of fabric can be interposed between the first and second layers. The thermoplastic foam can be, for example, ethylene vinyl acetate (EVA) foam. The fabric is preferably a mesh fabric formed from, for example, nylon, polyester, polycotton, cotton, acetate, or acrylic.